Hi Guys,
 
I am right now doing mixing for a project I was working on. All of a sudden there seems to be lots of stuttering, popping and clicking. Initially I was having Perfect Space as the reverb,  have since replaced it with the Sonitus reverb. I also have the Sonitus compression on the fx bins of a number of tracks. I am not sure why I am getting this problem suddenly as eveything was fine these past few weeks with this project file. Hope someone can advise. Thank you.

Not knowing your experience level, forgive me if this is obvious.  

Have you tried increasing the buffers on your audio interface.  It's the first thing I would do in this instance.